Genetic Diversity Estimates for Dichroa Species

Authors: Rinehart, Timothy - Tim; Reed, Sandra

Submitted to: American Society of Horticulture Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/2008
Publication Date: 7/21/2008
Citation: Rinehart, T.A., Reed, S.M. 2008. Genetic Diversity Estimates for Dichroa Species. American Society of Horticulture Science Meeting.

Interpretive Summary:

Technical Abstract: The genus Dichroa consists of 12 species of flowering plants in the family Hydrangeaceae, native to eastern and southeastern Asia. They are deciduous shrubs growing 1 to 3 meters tall in full sun or light shade and may exhibit evergreen growth habit in warmer climes. Flowers are hermaphroditic and similar to that of the related genus Hydrangea but lacking the sterile florets or large showy petals. Flowers cluster at terminal ends of branches but are also frequent along the length of the branch from axillary buds. The fruit is a glossy metallic purple-blue berry. Dichroa cultivars are not yet widely available but there is considerable interest in intergeneric hybrids between Dichroa febrifuga and Hydrangea macrophylla. Controlled crosses and open pollination have produced viable fertile offspring suggesting that these genera could freely interbreed in nature if native ranges overlapped. To better understand the genetic diversity within Dichroa we collected tissue samples from commercially available plants and those under development as ornamental cultivars. Many of these plants can be traced to a few wild-collected seeds suggesting most commercially available Dichroa cultivars are derived from a few seed sources. We also report significant variation in genome size, which may not adversely impact fertility of intergeneric hybrids, but could have profound effects on for future breeding. Some F1 intergeneric hybrids lack robust expression of H. macrophylla traits, presumably due to genetic imbalance between parents.